1. Field of the Invention
The invention relates to a support structure for stiffening one or more vibrating plates of an acoustic stringed instrument.
2. Description of the Related Art
With various acoustic stringed instruments, the aim is to make the vibrating plates of the instrument, especially the sound board and/or the back, as thin and as easily resonating elements as possible. But then again, certain stiffness requirements are set for this type of elements. The sound board, especially, should be sufficiently stiff and firm to withstand the strain caused by the strings.
In order for the instrument to produce an acoustic sound of sufficient volume and to be sensitively sounding, the mass of the vibrating part should be as small as possible. An even, pure tone over the instrument""s entire range of sound requires careful control of the vibrating parts, especially of the resonances of the sound board and the back.
Extremely contradictory requirements are thus set for the vibrating plates. On the one hand they should be easily resonating, and on the other stiff. Attempts have been made to solve this problem by using different kinds of support laths at suitable points.
By using support laths, it has been possible to make instruments meeting extremely high standards. However, due to the excessive mass amounting from them, not enough laths can be included to be able to tune the tone of the instrument over the entire range of sound in the best possible way.
The object of the invention is to eliminate these disadvantages.
To achieve this object, the support structure relating to the invention is characterised in that the support structure is formed by at least one sheet-like piece which is supported at least partly at a distance from the plate to be stiffened by means of one or more formed pieces arranged between the sheet-like piece and the plate to be stiffened, and that the entity formed by the sheet-like piece and the plate to be stiffened together is the shape of a lens thinning towards the edges in cross-section.
By means of the invention is achieved a lighter structure which is well controlled as concerns resonance, whereby the sound volume of the instrument increases and the purity of tone improves. Due to the smoother inner surfaces, the sound box functions more efficiently, thus also improving the quality of the tone.
It should be noted in particular, that when using the support structure relating to the invention, the actual plate to be stiffened can be made thinner than conventional structures.
Further preferable developments of the invention are disclosed in the dependent claims.